Consideration of Non-Structural Internal Debris in Siting of Blast Resistant Modules

Abstract

Blast resistant modules (BRMs) have become prevalent at petroleum refining and chemical processing facilities over the last decade. A primary rationale for utilizing a BRM is to allow a building housing essential personnel (e.g., operators) to be sited near the process units for which they are responsible. BRMs are selected based on a pressure-rating and response level (typically Low, Medium, or High). A common misconception is that a BRM will be undamaged and reusable for a specified blast overpressure rating, and such buildings are often incorrectly referred to as “blast-proof”. In order to absorb blast energy, the walls and roof of a BRM are designed to undergo transient accelerations and displacements. The allowable displacements are dictated by the selected response level, and that stated response level does not directly communicate the hazard associated with wall deflection and non-structural debris. Displacement and acceleration of a BRM wall can lead to significant non-structural internal debris hazards, as has been observed in testing programs and incident investigations. These hazards become more severe as the BRM blast rating and response level increases. Such hazards are sometimes overlooked when siting a BRM. A structural analysis of a BRM may be required to predict wall accelerations in order to quantify these hazards and properly site the BRM, rather than relying solely on a blast overpressure rating. This paper provides insight into the hazards associated with interior finish-out and wall-mounted items commonly observed in BRMs, and the means necessary to mitigate these hazards.